The treatment of focal macular diseases, and in particular ARMD, represents a major problem. Since the intact macula provides the vision that is required for reading, driving etc (but not for peripheral vision), the fact that there is no effective treatment for its degeneration means that many people increasingly retain peripheral vision only.
In order to solve this problem, it has been proposed that the retina should be moved. A more practical solution is to move the image from the macula to a point on the retina where there are healthy cells; although these cells may not function as well as the macular cells, an adequate degree of vision may be retained. Among other things, this is proposed in U.S. Pat. No. 6,197,057.
In particular, each of FIGS. 25, 27, 31 and 33 of U.S. Pat. No. 6,197,057 discloses a supplemental lens, i.e. an intraocular lens that is provided in addition to the natural, crystalline lens or to a biconvex IOL. All these drawings show a supplemental lens that is a conventional prism. The consequence is that the image is moved, away from the macula. Elsewhere in the specification, it is suggested that a Fresnel lens should be used as the supplemental IOL (column 9 line 13), and also that the lens should be “fresnel-shaped” (claim 14; again, this is in the context of a supplemental lens). It is unclear what form the “fresnel-shaped” lens should take.